@misc{ZaissPowellHaasetal., author = {Zaiß, Felix and Powell, John and Haas, Michael and Wahl, Johannes and Diegel, Christian and Schricker, Klaus and Bergmann, Jean Pierre and Hummel, Marc and Spurk, Christoph and Olowinsky, Alexander and Beckmann, Felix and Moosmann, Julian and Hagenlocher, Christian and Graf, Thomas}, title = {The influence of different core-ring intensity distributions on the capillary shape and resulting weld in laser welding of steel}, series = {Optics \& laser technology}, volume = {194}, journal = {Optics \& laser technology}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {0030-3992}, doi = {10.1016/j.optlastec.2025.114495}, pages = {1 -- 12}, abstract = {Laser welding was carried out using a co-axial core-ring beam, with independent control of the power to the core and the ring. The welding process was observed using high-power X-rays and high-speed imaging equipment. Adjusting the relative powers of the core and the ring beams was found to have profound effects on the shape of both the capillary created and the weld melt pool. Moderate laser power densities in the ring were found to increase the top diameter of the weld pool and reduce fluctuations in the welding process. High laser power densities in the ring led to the creation of a second capillary which largely acted independently of the capillary generated by the laser power in the core. At high power densities and welding speeds the two capillaries were almost completely separated in the direction of travel.}, language = {en} } @misc{ZaissPowellHaasetal., author = {Zaiß, Felix and Powell, John and Haas, Michael and Diegel, Christian and Schricker, Klaus and Bergmann, Jean Pierre and Spurk, Christoph and Hummel, Marc and Olowinsky, Alexander and Beckmann, Felix and Moosmann, Julian and Hagenlocher, Christian and Graf, Thomas}, title = {Core-ring laser welding : the influence of ring diameter on the capillary dynamics and the formation of pores in the resulting weld}, series = {Lasers in manufacturing and materials processing}, journal = {Lasers in manufacturing and materials processing}, publisher = {Springer Science and Business Media LLC}, address = {New York, NY}, issn = {2196-7229}, doi = {10.1007/s40516-026-00331-1}, pages = {21}, abstract = {Double-core fibers that deliver laser beams with adjustable amounts of power to the central core and the surrounding ring component of the fiber are of major interest for optimizing laser welding processes. However, the central focussed laser spot and the ring diameters are fixed by the fiber dimensions, the focusing optics, and the laser systems involved. This work investigates the influence of different ring beam diameters, with a constant central spot diameter, on the capillary dynamics and the formation of pores in the resulting welds in 1.4301 stainless steel (X5CrNi18-10, AISI 304). The different core-ring configurations were achieved using specially designed beam-shaping optics. The generation of pores during the welding process was examined by means of synchrotron X-ray imaging. The results show that different ring diameters have a profound effect on the melt pool geometry, the capillary shape and the location of the capillary collapse which gives rise to pore formation in the weld. In the examples presented here, larger ring diameters extended the melt pool in the direction of welding without contributing directly to the capillary evaporation. In this case the narrow, deep capillaries which are created by the core beam alone can bulge and collapse, trapping vapor and gas to create large pores. If, however, the ring beam has a small enough diameter, it can help to produce a wider capillary which does not trap gas and create pores in the same way. The mechanisms by which large bubbles in the melt can result in non-spherical pores in the weld are also explained.}, language = {en} } @misc{StaronBeckmannLippmannetal., author = {Staron, Peter and Beckmann, Felix and Lippmann, Thomas and Stark, Andreas and Oehring, Michael and Pyczak, Florian and Salgado, Mario and Hort, Norbert and Eckerlebe, Horst and Kainer, Karl Ulrich and M{\"u}ller, Martin and Schreyer, Andreas}, title = {In situ studies of light metals with synchrotron radiation and neutrons}, series = {Materials Science Forum}, journal = {Materials Science Forum}, number = {690}, issn = {1662-9752}, pages = {192 -- 197}, language = {en} } @misc{LiAmmannHelfensteinetal., author = {Li, Yafei and Ammann, Jeanine and Helfenstein, Julian and Williams, Tim G. and Levers, Christian and Mohr, Franziska and Diogo, Vasco and Zafeiriou, Rigas and Rolo, V{\´i}ctor and Beckmann, Michael and Hernik, J{\´o}zef and Kizos, Thanasis and Herzog, Felix}, title = {The potential of variable-rate technology for sustainable intensification of European arable farming}, series = {European journal of agronomy}, volume = {172}, journal = {European journal of agronomy}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {1161-0301}, doi = {10.1016/j.eja.2025.127868}, pages = {1 -- 17}, abstract = {Sustainable intensification of agriculture calls for reducing inputs while increasing yields. Variable-rate technology (VRT) enables the application of the right amount of resources at the right time and place to meet crop requirements. VRT remains relatively underutilized in European arable farming compared to Americas and Australia. Facilitating VRT adoption and other precision agricultural technologies in European arable farming requires understanding the pressing needs of farmers and proposing location-specific solutions to their problems. To address this gap, we conducted online surveys of experts in agricultural research, service, and primary production across seven European arable farming regions. Experts were asked to estimate the current and future adoption of VRT and to assess the role of relevant factors for adopting VRT in their regions. Furthermore, we asked about the challenges of fertilization, weed/pest control, and water management. Our results show a higher current and future VRT application for fertilization compared to weed/pest control and irrigation across all regions. The biggest barriers against VRT adoption in arable farming are cost, government regulations, and technology complexity. Moreover, our results show that VRT can more efficiently address the challenges of fertilizer application and weed/pest control, but has limited potential in addressing water management challenges, which need to be tackled by crop breeding, irrigation infrastructure, and water withdrawal rights. Our findings suggest that the low adoption of VRT in Europe is related to high cost and complexity of VRT, the substitute measures of VRT, and the limitation of VRT in addressing agroecological and policy-related challenges. Sustainable intensification thus requires a portfolio of technological, social, behavioral, and policy innovations.}, language = {en} } @misc{LiHelfensteinSwartetal., author = {Li, Yafei and Helfenstein, Julian and Swart, Rebecca and Levers, Christian and Mohr, Franziska and Diogo, Vasco and B{\"u}rgi, Matthias and Williams, Tim G. and Zafeiriou, Rigas and Zarina, Anita and Ammann, Jeanine and Rolo, V{\´i}ctor and Verburg, Peter H. and Beckmann, Michael and Hernik, J{\´o}zef and Kizos, Thanasis and Herzog, Felix}, title = {Agroecological and technological practices in European arable farming : past uptake and expert visions for future development}, series = {Land use policy}, volume = {153}, journal = {Land use policy}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {0264-8377}, doi = {10.1016/j.landusepol.2025.107553}, pages = {1 -- 14}, abstract = {Agroecological and technological innovations are two important approaches in the transition towards agricultural sustainability. We lack knowledge about how current agricultural contexts may influence future development pathways and the relative importance of the two approaches. This study explores the alignment between past uptake of agroecological and technological practices and future visions of agricultural development in seven European arable farming systems. By combining landscape mapping with farmer interviews, we first assessed the past adoption of agroecological and technological practices in each region. Then, we compared our findings with expert surveys about the future directions of agricultural development that can address local arable farming challenges. We found that in regions with intensive arable farming, agroecological approaches lagged behind the uptake of technological measures, both in the past and in future prospects. In low-intensity regions, we found large gaps between past uptake and future prospects of agroecological and technological practice adoption. These gaps need to be overcome in the context of future challenges of climate change adaptation and of environmental obligations. Our results indicate the need to take differentiated measures depending on farm management intensity and landscape conditions to enhance the future uptake of agroecological and technological solutions that can address the local challenges.}, language = {en} }